Cardiac arrhythmia is a class of serious heart diseases that threatens many people. Current arrhythmias diagnostic techniques seem to be partially efficient due to the application limitations either in time or in space. The paper presents a real-time continuous arrhythmias detection system (RECAD) platform based on the wireless sensor network technology. This system provides long-term real-time surveillance thanks to the low-resource and low power consumptions of ambulatory wireless ECG sensor (AWES). Moreover, the AWES is compact and friendly use, so it enables patients to lead a normal life every where (indoors or outdoors). RECAD platform contains four sub-systems: AWES, local access server, remote access server and remote surveillance server. Each subsystem is configurable to run in multiple operation modes according to different application scenarios. A lossless signal compression algorithm is adopted to reduce network traffics and a dedicated application layer protocol is provided to guarantee a real-time reliable on-line ECG analysis. This system is evaluated on about twenty patients at the hospital Gabriel Montpied of Clermont-Ferrand and the real-time results are similar to the HP telemetry system.